This is an old post but it suggest that the normal parking lots won't accommodate an rv. It does give information about a storage facility right nextdoor to a parking facility that does accommodate rvs.
I don't know how close or far from the terminal it is but there's alway Uber to get your gang to the terminal.
Parking motorhome at Port Everglades - Cruise Critic Message Board Forums
There's some information in this link that might be helpful.
Parking for Cruises in or near Fort Lauderdale, Florida | USA Today
I think the storage lot would be the most economical. I just went through this for a trip we're planning to Fort Myers. I thought it would be easy to find a place to leave our rv for a week or so while we stay with friends.
I finally found a nice secure lot less than a mile from our freinds' place for 60 bucks for the month. No one will do daily or weekly but 60 bucks seems like a good deal for secure parking while we're visiting.
Good luck and enjoy your cruise.